Electric-furnace apparatus for ores or minerals.



I. HECHENBLEIKNER. ELECTRIC FURNACELAPPARATUS FOR omzs 0R MINERALS.

APPLlCATION FILED DEC. 29. l8.

Patented Apr. 1,1919.

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INGENUIH HECHENBLEIKNER. 03? CHARLOTTE, NORTH CAROLINA, ASSIGNOR T SOUTHERN ELECTRO-CHEMICAL COMPANY, OF NEW YORK, N. A. CORPORA- TION OF NEW JERSEY.

ELECTRIC-FURNACE APPARATUS FOR. onus on. MINERALS.

Specification of lletters Patent.

Patented Apr. 1, 1919.

Application filed December 29, 1917. Serial No. 209,576.

Minerals, of which the following is a speci-v fication.

This invention relates to an apparatus for the treatment of ores or minerals and has case.

particular application to an apparatus for practising the method of treating potash and phosphate minerals as set forth in my co-pending application Serial No. 209,577, filed December 29, 1917, although I wish it to be understood that the invention is not limited in its useful application to this particular purpose.

In the method set forth in said co-pending application I subject a mixture charge of phosphate rock and a silicious mineral containing potash and a proper proportion of carbonaceous material to the action of an electric furnace to generate certain gases or vapors which are subsequently oxidized and purified, the purified vapors being subsequently further treated, as well known in the art to obtain phosphoric acid and potash. The mixture which I prefer to employ in the production of the gases is feldsplar (orthoclam), calcium phosphate and co e.

In the present instance it is my purpose to provide an apparatus wherein the phosphate rock and the feldspar are fed down I through a relatively long slowly revolving kiln into the electric furnace, the mixture of these two substances being preheatedin the passage down the kiln to the furnace. Just prior to, or practically at the point of entry to the furnace a charge of coke is mixed with the phosphate rock and feldspar and stoker mechanism is employed to distribute the mixture of coke, phosphate rock and feldspar evenly to the combustion chamber of the electric furnace, thereby forming a level bed of material which will be subjected to the flue action of the electrodes and which will not be banked or piled at one side of the furnace as is usually the By thus automatically and evenly stoking the material to the furnace I insure the best results as to the complete generation of the volatile gases, which is impossible with the ordinary style of electric furnace used for this purpose, inasmuch as .owing to the enormous heat generated when the furnace is in operation itis impossible to level or even the'material in the furnace by hand, and furthermore no provision can well be made for doing this even were it practicable, as the furnace must be substantially air-tight,'the"gases being oxidized as soon as or after they leave the furnace.

' Another object of my invention is so constructing my apparatus, especially the rotary kiln thereof that as the gases leave.

the furnace and are oxidized they will travel through the same in a relatively'long path so that certain impurities such as the silica and silicon fiuorid vapors (SiO and Sill) will be eliminated orrem oved from the outgoing gases while the latter are in the kiln and these impurities will be fed back into the furnace from which they may be removed with the slag. It is well known that in the treatment of a mixture of phosphate rock and silicious material, or silicious material containing potash, the materials used contain certain impurities which have a decided influence on the commercial operation of-the process. For instance, in such mixturescalcium chlorid is sometimespresent in quantities as high as 10%, and in the action of the electric furnace and under subsequent re-oxidation, gases or vapors are formed which contain not only phosphorus pentoxid, potassium oxid and carbon dioxid,.

but also certain impurities, such as silicon fiuorid, silicon dioxid and the like, 1n addition to some mechanical dust. The gases or I vapors while in the kiln will be subjected to a temperature sufliciently high to prevent the condensation of the phosphoric and phosphate gases yet low enough to allow of the removal or elimination of the im-. purities, such as $10 and SiF from the outgoing gases or vapors by absorption, through chemical reaction, by the 1ncom1ng charge, and thereforethe length and di ameter of the kiln should be proportioned to the amount of the charge for the furnace operation. I

Still a further object of the invention is to provide an apparatus WhICl), will e body the desired features of simplicity anddurability and which may be installed' and operated at a relatively low cost.

With the above recited objects and others of a similar nature in view my invention consists in the construction, combination and arrangement of parts set forth in and falling within the scope of the appended claims.

In the accompanying drawings Figure 1 is a new partly in vertical longitudinal section and partly in elevation of an apparatus embodying my invention.

Fig, 2 is a horizontal sectional viewtaken through the electric furnace.

I ings in detail the letter A indicates the electric furnace provided with the usual carbon electrodes 1 and the tap hole 2 for the slag. This furnace is made practically air-tight, as is desired in an apparatus of this type, as the entry of air into the furnace would result in the destruction of the carbon electrodes.

Adjacent its upper end the furnace is formed with an extension 3 having a passage 4 through which the charge of material.

passes on its way into the furnace, and a gas exit passage 5 leading from the furnace to the rotary kiln B, these two passages 4 and 5 being separated by the partition wall 6. The rotary kiln B is mounted upon a suitable supporting frame C, the kiln being supported at its upper end upon a pipe neck connected with the dust collector D, the opposite end of the kiln being supported upon the collar 8 forming part of the wall of the gas exit passage 5. As will be seen by reference to Fig. 1 the rotary .kiln is inclined upward from the electric furnace to the dust collector and is intended to be revolved by any suitable mechanism, such as is conventionally shown at E in said Fig. 1, the ends of the kiln finding bearings on the pipe neck 7 and the collar 8 as just described. The pipe neck 7 connecting the kiln with thedust collector D is provided with a suitable hopper 9 into which is dumped certain ingredients of the mixture to be fed into the electric furnace, such as the phosphate rock and the feldspar, and perhaps some sand. Under the rotation of the kiln this material is fed slowly down the latter at the discharge end of the rotary kiln. This material which is shown at F drops onto the floor 10 of the feed passage 4 and is there mixed with coke or other carbonaceous material indicated at G, in Fig. 1, such coke being fed down through the spout 11 and into the hopper 12 which discharges into the passage 4, as will be clearly understood by reference to Fig. 3. This hopper is provided with a hinged controlling gate 13 for the obvious purpose of controlling the supply of coke allowed to enter the electric furnace or to form a component part of the mixture being delivered to the furnace.

The now complete charge consisting of the feldspar, phosphate rock and coke is mixed in the feed passage 4 and fed into the furnace by means of the reciprocating watercooled plungers 14: of the stoking mechanism which is indicated as an entirety by the letter H. In the present instance there are a number of these stokers shown at 14', each comprising a hollow, cylindrical body sliding in the way or port 15 of the vertical wall of the extension 3, and is water-cooled by water admitted through the inlet pipe 16, the water passing out through the outlet pipe 17; Each plunger is provided with a stem 18 connected with the piston head 19 worln'ng in a cylinder 20. This piston is reciprocated in its cylinder by fluid pressure, through water, air or steam admitted and exhausted through the pipes 22, as well understood in mechanisms of this character.

As the charge of feldspar and phosphate rock drops onto the floor 10 of the passage 4 it is there mixed with the coke and pushed by the plungers of the stoking mechanism into the combustion chamber of the electric furnace. In prior apparatus of this general type where the coke is fed into the kiln with the rock and sand mixture such coke in its passage through the kiln becomes heated and partially consumed so that its efficiency as areducing agent is greatly impaired by the time it enters the furnace. Furthermore, with the usual type of apparatus where the mixture was simply fed into the furnace by gravity, it usually formed a pile or bank at one side of the furnace instead of being evenly distributed or leveled over the entire combustion zone of the latter. This was due to thefact that no adequate means had been provided for spreading or leveling the charge in the electric furnace. By the arrangement of feed passage and stoking mechanism as shown herein I am enabled to feed fresh coke mixed with the preheated rock or minerals evenly and uniformly to the furnace so that the bed of material in the furnace will be completely subjected to the heating action of the electrodes and cated, the rotary kiln is of such length and diameter that the impurities in the gases or vapors, such as the silica and silicon fluorid, are removed or eliminated from the outgoing gases and under the rotation of the kiln are carried back into the furnace and drawn ofi' with the slag. Of course the length of the kiln will depend to a considerable degree upon the amount and'character of the charge, in some instances a kiln of the length of 60 feet being admirably adapted for an ordinary charge. Phosphorus and potash vapors and gases, however, .require a lower temperature for condensation and under the action of the suction fan J are drawn through the kiln and pipe section 7 to the dust collector D where any fine mechanical dust which may have been drawn through the kiln is trapped or caught, as the gases pass around the usual partition d in the dust collector. After the potash and phosphorus vapors or gases pass through the dust collector they are conducted to the usual scrubbing system or to an electric precipitator where they are condensed and concentrated, as is well understood in this art.

As the gases leave the electric furnace and just before they enter the rotary kiln they are subjected to oxidization through air or oxygen admitted through the air inlet K which preferably communicates with the upper portion of the passage 5, the air being drawn in at this point under the velocity of the gases passing out of the electric furnace to the rotary kiln.

I have simply described my electric apparatus briefly in connection with the treatment of certain minerals or ores in order that its operation might be the more readily appreciated, but I wish it to be understood that I do not confine the use of the apparatus to the treatment of the particular materials hereinbefore mentioned. Furthermore, while I have herein shown and described one particular embodiment of my invention I WlSh it to be understood that I do not confine myself to all the precise details of construction herein set forth by way of illustration, as modification and variation may be made without departing from the spirit of the invention or exceeding the scope of the appended claims.

What I claim is: 1

1. In an apparatus of the class described, the combination with an electric furnace, of a mixing chamber communicating therewith and forming an extension thereof, a horizontally inclined rotary kiln connected with the mixing chamber and having a charge inlet distant from the mixing chamber and through which kiln a charge of ore or rock is adapted to be fed to said chamber, means independent of the kiln for sup- Ccpi.

of a mixing chamber communicating therewith, means for feeding a charge of rock or ore to the mixing chamber, separate means for feeding coke to the mixing chamber where it is mixed with the rock and ore to form a furnace charge and stoker mecha nism including water-cooled plungers op erating in the mixing chamber for feeding a charge from said chamber into the furnace.

3. In an apparatus of the class described, the combination with a furnace, of a mixing chamber communicating therewith and forming an extension thereof, a rotary kiln leading to the mixing chamber and having a charge inlet distant from the mixing chamber and a discharge outlet at the mixing chamber, a coke hopper independent of the kiln also leading to the. mixing chamber, and stoker mechanism operating in the mixing chamber to feed a charge therefrom into the furnace.

4. In an apparatus of the class described, the combination with an electric furnace, of a mixing chamber extending therefrom and communicating therewith, a rotary kiln con nected with the mixing chamber and having a charge inlet distant from the mixing chamher and a discharge outlet leading to the -mixing chamber, a separate hopper also rately supply materials to the mixing chamber to constitute a furnace charge, stoker mechanism working in the mixing chamber for feeding the charge from the mixing chamber to the electric furnace where the mixture is vol atilized in the heatof the .furnace, and means for oxidizing the gases passing from the furnace back to the kiln.

5. In an apparatus of the class described, the combination With a furnace, of a mixing chamber communicating therewith, a rotary kiln for feeding certain constituents of a furnace charge to the mixing chamber, said constituents traveling substantially throng out the length of the kiln, means for separately feeding other constituents of the charge to the mixing chamber, means for feeding the complete charge from the mixing chamber to the furnace, and nieans asso- 

